This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The yeast nuclear RNase P is responsible for the maturation of the 5'end of precursor tRNAs. There are several lines of evidence that lead us to believe that RNase P has additional substrates and we have recently identified several candidiates. Work to attempt the identification of interacting partners outside the known core of RNase P is being carried out. Using novel affinity tags, we are able to rapidly isolate the holoenzyme and expect to find interacting proteins that were lost during the initial arduous purification that led to the identification of the RNase P core. These interacting partners will be investigated for their roles in the processing of novel substrate candidates recently identified in our lab.